Jet lag from Sydney to London: what to expect
Fly Sydney to London and local time runs 11 hours behind your body. Land at 21:15 and your body still thinks it's 08:15 in Sydney. For your body, that's morning. At 23:00 in London, it's 10:00 for you.
That's a westward shift: your clock has to move later, which is the way it drifts on its own S1. Expect to be sleepy early in the evening for the first few days, and awake before your alarm S1.
At 11 hours you're close to the far side of the world, where a clock could in principle shift either way. Adapting by delay is the more common route at that distance S1.
How long does jet lag last from Sydney to London?
Unaided, westward shifts settle somewhat faster than a day per time zone: about 8 days for this one. S6 S7
This plan targets 7 days.
That's what the plan aims at, not a promise — bodies vary.
For this trip that's 1 day sooner than the unaided estimate, on the effort level that fits around a working day.
On night one, the evening after you land, the plan's bedtime is 21:00, early by London's clock. It holds there for 5 nights, then moves to 23:00 by night 7.
Studies of aircrew point the same way: after large shifts, westward adaptation runs roughly 50% faster than eastward S6 S8. This trip is on the quick side of that.
What does the plan say for a typical Sydney to London flight?
- Departs
- 11:00 Sydney time
- Lands
- 21:15 London time
- In the air
- about 21h 15m (estimate)
- Light, the first full day
- 16:55–17:55 Seek bright light (delay shift)
- Keep it dim, the first full day
- 02:00–04:00 Avoid bright light (sunglasses / dim room)
- Last caffeine, landing day
- 10:00 on the plane
- Caffeine after landing
- 02:00–13:00
- Nap after landing
- 22:45 Nap when you can lie down, up to 90 min
- First night's sleep
- 21:00–05:30 the evening after you land
Westbound flights often go by day, so this example leaves Sydney at 11:00 and lands in London at 21:15 late at night, after about 21h 15m in the air.
The flight time is our estimate for a nonstop from the distance, and the trip is set in January. It's the default traveler from the calculator: usually asleep 23:00 to 07:00, no melatonin, Real Life effort.
That's longer than any regular nonstop flight, so in practice this trip has a stop. For a trip with connections, the calculator takes your first departure and your final arrival.
In July the gap is 9 hours, not 11, because Sydney and London change their clocks in opposite halves of the year.
The plan puts about 3 hours of sleep on board, from 18:00 to 20:45 London time, ending half an hour before you land. What's left of that night becomes a nap on the ground at 22:45: "Nap when you can lie down, up to 90 min".
You land at 21:15 and stay up through the local night, apart from the 22:45 nap: at 02:00 in London your body thinks it's 13:00 in Sydney, the middle of its day. It adds a 30-minute nap at 10:25. The first full night comes the next evening, at 21:00.
The day before you fly, the plan keeps your morning dim, 07:00–09:00 Sydney time, and the sun is up in Sydney by about 06:02 in January, so plan on sunglasses for the commute.
Your last coffee on the plane is at 10:00 London time. After you land the plan opens caffeine again at 02:00, until 13:00: at 02:00 your body thinks it's 13:00 in Sydney, the middle of its day, and the plan keeps you up through the night on purpose.
January days are short in London: about 9 hours of daylight. In January the sun sets in London at about 16:29, so the 16:55 light step the day after landing comes after dark. It has to be bright indoor light.
You land too late in the day for a light step on landing day, so the first one is the next day, at 16:55.
Note the order: the plan keeps you out of bright light until 16:55, then sends you outside. Light before your body's low point pushes the clock later S1, which is only welcome once the low point has passed.
What helps after flying west to London?
Going west, you want light before your body's low point, which usually means bright light in the evening and staying up a little later S1. Bright light first thing in the morning works against you. East vs west explains why this direction is the easier one.
On a shift this size, starting before you fly pays off. The Frontiers review describes moving bedtime 30 to 60 minutes later each day for 3 to 4 days before a westward trip S1. The plan's version is one night: bed at 00:00 the night before you fly, an hour later than usual.
And the flight home from London?
London to Sydney is the same 11 hours the other way, eastward. It's the harder direction: about 11 days unaided, and the plan targets 8. Jet lag from London to Sydney has the details.
More routes from Sydney
Sources
Numbered from the site-wide source registry — every Delagged page uses the same numbering.
- S1 Roach GD, Sargent C. Interventions to Minimize Jet Lag After Westward and Eastward Flight. Frontiers in Physiology, 2019;10:927. doi:10.3389/fphys.2019.00927
- S6 Waterhouse J, Reilly T, Atkinson G, Edwards B. Jet lag: trends and coping strategies. The Lancet, 2007;369:1117–29. doi:10.1016/S0140-6736(07)60529-7
- S7 Eastman CI, Burgess HJ. How to travel the world without jet lag. Sleep Medicine Clinics, 2009;4:241–55. doi:10.1016/j.jsmc.2009.02.006
- S8 Samel A, et al. Aircrew adaptation after transmeridian flights, 1995. As cited in Waterhouse et al., The Lancet 2007 (S6). Full text Cited via S6.